content/browser/renderer_host/backing_store_manager.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "base/callback_forward.h"
  12 #include "base/process.h"
  13 #include "ui/gfx/rect.h"
  14 #include "ui/gfx/size.h"
  15 #include "ui/surface/transport_dib.h"
  16
  17 namespace content {
  18 class BackingStore;
  19 class RenderWidgetHost;
  20
  21 // This class manages backing stores in the browsr. Every RenderWidgetHost is
  22 // associated with a backing store which it requests from this class.  The
  23 // hosts don't maintain any references to the backing stores.  These backing
  24 // stores are maintained in a cache which can be trimmed as needed.
  25 class BackingStoreManager {
  26  public:
  27   // Returns a backing store which matches the desired dimensions.
  28   //
  29   // backing_store_rect
  30   //   The desired backing store dimensions.
  31   // Returns a pointer to the backing store on success, NULL on failure.
  32   static BackingStore* GetBackingStore(RenderWidgetHost* host,
  33                                        const gfx::Size& desired_size);
  34
  35   // Makes a backing store which is fully ready for consumption, i.e. the
  36   // bitmap from the renderer has been copied into the backing store.
  37   //
  38   // backing_store_size
  39   //   The desired backing store dimensions, in DIPs.
  40   // bitmap_section
  41   //   The bitmap section from the renderer.
  42   // bitmap_rect
  43   //   The rect to be painted into the backing store, in DIPs.
  44   // scale_factor
  45   //   The device scale factor the backing store is expected to be at.
  46   //   If the backing store's device scale factor doesn't match, it will need
  47   //   to scale |bitmap| at paint time. This will only be out of sync with the
  48   //   backing store scale factor for a few frames, right after device scale
  49   //   changes.
  50   // needs_full_paint
  51   //   Set if we need to send out a request to paint the view
  52   //   to the renderer.
  53   static void PrepareBackingStore(
  54       RenderWidgetHost* host,
  55       const gfx::Size& backing_store_size,
  56       TransportDIB::Id bitmap,
  57       const gfx::Rect& bitmap_rect,
  58       const std::vector<gfx::Rect>& copy_rects,
  59       float scale_factor,
  60       const base::Closure& completion_callback,
  61       bool* needs_full_paint,
  62       bool* scheduled_completion_callback);
  63
  64   // Returns a matching backing store for the host.
  65   // Returns NULL if we fail to find one.
  66   static BackingStore* Lookup(RenderWidgetHost* host);
  67
  68   // Removes the backing store for the host.
  69   static void RemoveBackingStore(RenderWidgetHost* host);
  70
  71   // Removes all backing stores.
  72   static void RemoveAllBackingStores();
  73
  74   // Current size in bytes of the backing store cache.
  75   static size_t MemorySize();
  76
  77  private:
  78   // Not intended for instantiation.
  79   BackingStoreManager() {}
  80
  81   DISALLOW_COPY_AND_ASSIGN(BackingStoreManager);
  82 };
  83
  84 }  // namespace content
  85
  86 #endif  // CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_